Helicopters are used to great advantage in Search and Rescue (SAR) operations. By conducting SAR operations from the air, greater distances can be searched, and otherwise inaccessible areas reached. Once an accident victim, downed airman or other person in need of assistance is located, the helicopter can then be used to retrieve that person. In many instances, it is not possible or safe for the helicopter to land. For example, the person to be rescued may be in the water and sea conditions may be too rough for the helicopter to land, or the helicopter may simply not be configured for water landing. When the person being rescued is on land, the helicopter may be unable land because of rugged terrain, trees, hostile ground forces, or other reasons. In such cases, a hoist in the helicopter can be used to lower a rescue hook, a harness, a basket or other retrieval device at the end of a cable, and then lift the rescued person up into the helicopter.
Typically, the hoist is located above a door or other ingress/egress point on the helicopter, and positioned so that the rescued person is at the same level with the door when the cable is completely taken up. So that the hoisting mechanism will not be jammed or damaged, it is necessary to shut off the hoist upon completion of the hoist operation, i.e., when the rescued person is at door level. An automatic limit switch or similar device is generally incorporated into the hoist for this purpose. A large plate, ball or other shape is typically located at the terminal end of the cable (i.e., just above the rescue hook or other mechanism for attachment to the person being rescued, or to the retrieval device). As the cable is hoisted up and the rescued person reaches the level of the helicopter door, the plate, ball or shape engages a contact on the hoist and trips the limit switch, thereby stopping the hoist.
On occasion, a rescue cable may become frayed or otherwise damaged, and the rescue hook (or other connection fitting) becomes unattached from the cable end. If there are remaining rescue operations to be performed, it is important that a replacement hook (or other connection fitting) be quickly and safely attached to the cable. It is also important that the automatic shut-off mechanism for the hoist remain operational. To date, however, there are no known devices that permit quick and simple attachment of a replacement hook under field conditions, while maintaining the operability of an automatic hoist shut-off.